Relative humidity apparatus



- 1968 H. KNIERIEM ETAL 3, 08, 60

RELATIVE HUMIDITY APPARATUS Filed Dec. 5, 1965 INVENTORS, HermanKn/Ler/em BY Hora/0'0. De shon United States Patent;

3,408,860 RELATIVE HUMIDITY APPARATUS Herman Knieriem, Midland, andHarold D. De Shon,

Bay City, Mich., assignors to The Dow Chemical Company, Midland, Mich.,a corporation of Delaware Filed Dec. 3, 1965, Ser. No. 511,367 6 Claims.(CI. 73-73) This invention relates to apparatus for indicating theamount of water vapor present in dry cleaning solvent, and particularlyto a humidity measuring meter for use with dry cleaning apparatus.

It has long been known that too much or too little water content in drycleaning solvent could result in wrinkling, shrinkage, or redeposition(graying), on the fabric being cleaned.

The usual way to determine the amount of moisture present in the solventinvolves removing a sample of the solvent from the cleaning apparatusand then analyzing to find the moisture content of the sample. Suchtests are time consuming, made on a spot basis only, and often theiraccuracy is affected by the type and/ or amount of the detergent presentin the solvent and by the non-volatile matter present in the solvent.

Accordingly, a principal object of this invention is to provide animproved device for measuring the water moisture content in a drycleaning solvent or the like.

Another object of this invention is to provide an improved, simple toinstall, easy to use device for continuously measuring the relativehumidity of solvent in dry cleaning equipment.

In accordance with this invention, there is provided a cup-like housinghaving a transparent cover. A vapor input line extends into the centralpart of the housing, opening towards the back of the housing. A vaporoutput line is coupled through the housing wall remotely from the openend of the input line. A shield is disposed across the output opening inthe housing to prevent the back splattering with solvent of a carddisposed in the housing and having a plurality of patches thereon whichchange color in accordance with the moisture content of the vaporentering and leaving the housing.

Because the relative humidity of the solvent vapor is directly relatedto the amount of water in the solvent, the humidity gauge of thisinvention, when coupled between the solvent tank, for example, and apoint on the dry cleaning apparatus where solvent is pumped over anupwardly extending bend in one of the solvent lines, continuouslymonitors the moisture (water) content of the solvent in the dry cleaningapparatus.

The invention, as well as additional object and advantages thereof, willbest be understood when the following detailed description is read inconnection with the accompanying drawing in which:

FIG. 1 is a front elevational view, in section, of humidity measuringapparatus (with the gauge card removed) in accordance with thisinvention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1, and

FIG. 3 is a front elevational view of a humidity gauge card inaccordance with this invention.

Referring to the drawing, and particularly to FIGS. 1 and 2, there isshown humidity measuring apparatus, indicated generally by the numeral10, which includes a cylindrically shaped housing 12 having side walls,a closed end 13 and a removable closed end part 18 having a transparentface which is adapted to fit in a substantially gas tight manner overthe side walls 15.

A vapor inlet tube 14 enters the housing 12 through the side wall 15 andhas its open end 24 facing towards the end 13 of the housing.

A humidity indicating card holder 20 is disposed within the housing 12,held in place by means of welds 22 securing it to the inlet tube 14, sothat it is positioned between the inlet tube and the transparent face ofthe end part 18.

The humidity indicating card 26, shown in FIG. 3, has tabs 28, 30 on itwhich fit into slots in the outwardly extending end parts of the holder20.

A vapor outlet tube 16 extends through the wall 15 of the housing, theopen end of the tube being covered by a shield or sleeve 24 whichprevents accidental spraying of the card 26 in case solvent isinadvertently momentarily surged through the output line.

The humidity indicating card 26 is made of a blotter type paper havingan area, the peripheral area 42, for example, of a fixed color.

A plurality of colored patches 32, 34, 36, 38, 40, for example, areprovided on the card 26. The patches are composed of cobalt chloride invarious concentrations whereby the patches change color as the relativehumidity to which they are exposed increases. The relative humidity isread as being that designated for the colored patch which most nearlymatches the fixed color in the peripheral area 42, for example. In onesuch card the patch 32 represented 30% relative humidity, the patch 34represented 40% relative humidity, the patch 36 represented 50% relativehumidity, the patch 38 represented 60% relative humidity, and the patch40 represented relative humidity when the respective patches matched thecolor of the peripheral area.

The patch 40, if pink in color, also represented over relative humidity.

In operation, the input line 14 is coupled to the top of the solventstorage tank and the output line is coupled to the top of a loop in thesolvent flow line (where a so called vacuum breaker element would beinstalled, for example). Thus, as solvent flows over the loop, a vacuumtends to be created, drawing vapor from the solvent tank through theinput line 14, housing 12, and into the output line 16.

The vapor from the solvent tank contains water in an amount which is inequilibrium with the water in the solvent. Thus, the color of thepatches on the card 26 in relation to the color of the peripheral area42 is an indication of the relative moisture content in the solvent atthe temperature condition existing in the vapor.

It has been found that the card 26 is not affected by the solvent vaporor the non-volatile materials in the solvent, but responds substantiallyonly to the water moisture content of the vapor. There are, of course,no moving parts to become fouled or damaged. Further, the type andamount of detergent used in the solvent system do not affect the card26.

Because this device provides a continuous means for monitoring thesolvent relative humidity, the operator of the dry cleaning apparatuswill know when to add or remove water from the solvent.

What is claimed is:

1. Relative humidity measuring apparatus comprising:

(A) an enclosed generally cylindrically shaped housing having an endwall, side wall, and a second end wall having a transparent face;

(B) a vapor inlet conduit, said vapor inlet conduit extending throughsaid side walls and having an open end facing toward but spaced fromsaid end wall;

(C) a vapor outlet conduit, said vapor outlet conduit extending throughsaid side walls remote from said open end of said vapor inlet conduit;

(D) a backflow diverter element, said diverter element being disposedover said vapor outlet conduit within said housing;

3 (E) a humidity indicator holding bracket fixedly disposed in saidhousing, and Y (F) a humidity indicator-including a card having aplurality of deposits thereon which each change color when exposed tospecific amounts of humidity. 2. Apparatus in accordance with claim 1,.wherein said deposits each contain cobalt chloride in a specifiedconcentration.

3. Apparatus in accordance with claim 1, wherein said card is made of ablotter-like .paper.

4. Apparatus in accordance with claim 1, wherein said card has tabsthereon which fit in said bracket.

5. Apparatus in accordance with claim 1, wherein housing issubstantially gas tight.

6. Apparatus in accordance with claim 1, wherein said open endof saidinlet conduitis-near the longitudinal axis of said housing.

References Cited UNITED STATES PATENTS 8/1955 Blinn 73-73 2,716,3382,949,336 8/1960 Michaela et al. 73-73 2,967,084 1/1961 Reitz 73'-73RICHARD C. QUEISSER, Primary Examiner.

C. IRVIN MCCLELLAND, Assistant Examiner.

1. RELATIVE HUMIDITY MEASURING APPARATUS COMPRISING: (A) AN ENCLOSEDGENERALLY CYLINDRICALLY SHAPED HOUSING HAVING AN END WALL, SIDE WALL,AND A SECOND END WALL HAVING A TRANSPARENT FACE; (B) A VAPOR INLETCONDUIT, SAID VAPOR INLET CONDUIT EXTENDING THROUGH SAID SIDE WALLS ANDHAVING AN OPEN END FACING TOWARD BUT SPACED FROM SAID END WALL; (C) AVAPOR OUTLET CONDUIT, SAID VAPOR OUTLET CONDUIT EXTENDING THROUGH SAIDSIDE WALLS REMOTE FROM SAID OPEN END OF SAID VAPOR INLET CONDUIT; (D) ABACKFLOW DIVERTER ELEMENT, SAID DIVERTER ELEMENT BEING DISPOSED OVERSAID VAPOR OUTLET CONDUIT WITHIN SAID HOUSING; (E) A HUMIDITY INDICATORHOLDING BRACKET FIXEDLY DISPOSED IN SAID HOUSING, AND (F) A HUMIDITYINDICATOR INCLUDING A CARD HAVING A PLURALITY OF DEPOSITS THEREON WHICHEACH CHANGE COLOR WHEN EXPOSED TO SPECIFIC AMOUNTS OF HUMIDITY.